Automatic low-pressure control apparatus for compressors



May 1l 1926.

L.- F. HOFFMAN AUTOMATIC LOW PRESSURECONTROL APPARATUS FOR COMPRESSOR S I' Filed June 2;;1924 2 sheets-sheet;

WVM/719 Lo/1 F.' Hoffman May 11 ,41926. l

` ll.. F. HoFFMAN AUTOMATIC Low PRESSURE CONTROL'` APPARATUS Fon' couPREssoas A Fild June"l 1924 2 Sheetsl-Sheet 2 Patented May 1l, 1926.

UNITED' STATES PATENT OFFICE.

LEON" F. HOFFMAN, OF FRANKLIN, PENNSYLVANIA, ASSIGNOR T0 CHICAGO PN'- MATTO TOOL COMPAN Y, 0F NEW YORK, N. Y., A CORPORATION 0F NEW JERSEY.

i AUTOMATIC LOW-PRESSURE CONTROL APPARATUS FOR COMPRESSORS;

Application led .Tune 2, 1924. Serial No. 717,228.

This invention relates to automatic control apparatus for fliud compressors, pumps,

and the like and particularly to apparatus.

of this type which is responsive to low pressures, especially such extremely low pressures as below vtwelve pounds toy the square inch. f

The use of low fluid pressures, which was formerly restricted largely to the transmission ot' illuminating gas and in pneumatic tube systems, is steadily increasing with the industrial development and wide use of oil burners, of humidifying syst-ems and with its adaptation to the agitation of liquids of all sorts in the many forms of wet processes and treatments both chemical and otherwise, The ordinary -types ot' automatic control apparatus which function properly with high pressures are not suitable with low pressures since they frequently fail to operate at all on pressures below twelve pounds to the square inch and their operation at pressures slightly higher is inclined to be erratic.

Among the objects of the invention are to provide apparatus of the described type which operates efliciently and positively at v`any desired low pressure, toeffect the above objects by the use of adapters readily applied to the ordinary forms of unloader and unloading valves, and in general to improve prior devices in the matter of effective range and sensitivity to widely varying pressures.

In order to make clear the nature of .the invention one concrete embodiment thereof is shown in the accompanying drawings, in which:

Fig. 1 is a side elevational view partly in section of a *compressor provided with control apparatus sensitive to low pressures; and` v Fig. 2 is an enlarged sectional view of an unloader and an unloading vvalve both equipped with the invention.

Fig. 1 illustrates a compressor and its controlling apparatus with the invention applied thereto, A being the compressor, B its piston, C fluid pressure operated unloading valves of any suitable or desired type, such as that disclosed in U. S. Patent No. 1,27 5,-

issued August 13, 1918 to 1V. H. Callan,

' and D unloadcr or pilot valves subjected to receiver pressure entering the same through pipes d and adapted to control the operation of the unloading valve C. The unloader valves illustrated are of the difieren- ,tial type disclosed in U, S. Patentl No. 1,- 224,272 issued May 1, 1917 to W. H. Callan brief description ofthe same may be of value in making clear the operation of the invention. Each of the unloading valve assemblies C comprises a valve seat c, a valve keeper c in spaced relation to the former with one or more plate valves c2 disposed therebetween and urged toward the seat by springs o3, a stem c4 uniting seat and plate and holding' the inner valve assemblyin place in the compressor cylinder, for which purpose a sleeve or cylinder c5 threaded into a cap plate of has a cross piece c engaging the end of stem c4. A piston o8 is slidable in cylinder o5 and is'adapted to act through a plunger c upon a valve lifter 01 slidably mounted on stem c* and normally held out of engagement with valves c2 by a spring c, The motive fluid for acting upon piston 0B is admitted through a pipe 012 from the unloader valve assembly D which comprises a hollow casing d hav- I ing a closure d2 upon which is slidably mounted within the casing a valve d3 adapted to cooperate either with a circular seatl on casing d or with a seat on the end of closure d? to close the bore through the latter. The lower end of valve d3 is engaged by plate Z4 backed by a sprin d, the tension of which is controlled y adjusting screw al provided with a lock nut df, the

spring being adapted normally to hold the valve against the closure d2. One or more small vents d8 permit restricted passa e of- 3 comprising the present invention are arranged for convenient.attachment to the unloader and unloading valves as shown. Each adapter consists of a casing formed of twb dished members 4 and 5 arranged to be bolted or otherwise secured together. The lower member 5 has a stem 6, adapted to be threaded into or otherwise secured in the opening of the closure d2 of unloading valve D or in the cap plate 013 of' the unloading valves C. The pipes d and c12 formerly connected directly to the unloader and unloading valves respectively are now connected to members 4 of the adapter. 1Within the adapter casing is a diaphragm 7 interposed between the pressure area of the valve and the source of motive fluid for actuating the' same. Means are provided for transmitting to the .pressure area of the valve, such as the valve member d of unloader D or the piston e8 of unloading valve C, not only a portion of the motive fluid which acts upon the diaphragm 7 but also the movement of the latter. The means may take the form of a tube 8 secured to the diaphragm 7 as by a plate 9 engaging the diaphragm on one side and a nut 10 engaging it on the other, whereby the diaphragm is clamped therebetween, the tube being arranged. for sliding movement in the bore of stem 6 and of a length to rest upon or lightly engage the valve Z3 of the' unloader `D or the piston o8 of unloading Valve C, one or more openings or slots 11 permitting motive fluid to pass `freely into the chambers adjacent the pressure areas of valves d3 and piston e8. Thus the adapter increases the pressure area of the member to be actuated to the extent of the effective pressure. area of the diaphragm 7 and by making the diaphragm of proper size unloader and unloading valves can be -made sensitive to very small changes in receiver pressure.

The operation of the apparatus is as follows; V'Vhen the receiver pressure exceeds the amount predetermined by the adjustment of spring d of unloader or pilot D,

vvalve da subjected to the pressure of the motive Ifluid (entering through pipe cl) on its upper face or pressure area and upon tbe diaphragm, 7 as transmitted through the stem 8, moves from its closed position (Fig. l) to its open position (Fig. 2). Motive fluid then passes through the restricted ports d8 into pipe. 012 and thence to the unloading valves C where itacts upon diaphragms 7 of their adapters and through tubes 8 upon pistons ofy which on moving acty upon plungers 'C9 and valve lifters 010 to force valves c2 ofi1 their seats, thereby unloading the compressor. The compressor remains unloaded until falling pressure in the receiver permits spring (Z5 to restore. valve d to its closed position (Fig. l) whereupon the pressure fluid inthe chambers of the unloading valves and in pipe c12 escapes into the lower part of casing d and thence by a suitable vent to atmosphere'. This reliaf of pressure permits springs 011 to restore lifters c1 and their cooperating members to their normal inoperative position whereupon valves c2 resume their normal function as compressor inlet valves. In case it is desired to suspend the automatic operation of unloader and unloading valves equipped with adapters 3, manual means for actuating the same are provided. One arrangement for this purpose comprises a manual control 12 mounted for rotative, movement on the stem or connection 13 secured to casing member 4 of the adapter and to, which pipe d or pipe c is attached, control 12 having a cam surface 14 arranged to engage a pin plunger'l to force the latter against nut 10 on tube 8 whereby the latter is utilized to actuate va ve Por piston 08. From the above it will be apparent that the present invention adapts automatic control apparatus for compressors to any desired pressure', that the adapter devices for this purpose are readily applied ta existing types of unloader i these devices do not interfere with the normal operation of such valves but merely serve to increase the effective pressure areas thereof, and that the adapters are relatively inexpensive to manufacture and when installed in automatic control systems by ma kingslight changes in the pipe connections they operate in a positive manner to increase the-low pressure range of such apparatus. W'hile but one form of the invention has been herein disclosed and described, it is to be understood that the invention is not limited to the specific details thereof but covers all changes, modifications and adaptations within the scope of the appended claims. f

Having now described my invention and the manner of its use, what I. claim and desire to' secure by Letters Patent is:

. 1. The combination with a fluid compressor and 'automatic control apparatus therefor, of means inserted in the fluid pressure conduits to said control apparatus for adapting the same to pressures below the range of response of said apparatus. i

2The combination with a fluid compres` sor and automatic control apparatus therefor. of means readily applied to .said control apparatus for adapting the saine to pres. sure below the range of response ot' said apparatus and manual means operable through said first named means for suspending the automatic operation of said apparatus.`

3. In combination. a compressor havirm unloader and unloading valves elieetini;A automat-ic control thereof in response to receiver pressure. and means readily applied to said valves for increasing the efl'ective areas thereof subjected to receiver pressure,

and unloading Valves, thatv lill thereby to'render said valves responsive to maticcontrol of the compressor in response .to receiver pressure, means inserted in the fluid pressureconduits to said valves for increasing the effect-ive areas thereof subjected to receiver pressure, thereby to render `said valves responsive to low pressures, and manual means operable through said first named means for suspending the automatic operation of said valves.

5. In combination, a compressor having unloader and unloading valves effecting automatic-control of thecompressor in response to receiver pressure, and means applied to at least one of said valves adapting the saine to pressures below its normal range of response, said means increasing the presj sure area of said valve responsive to receiver pressure.

6. In combination, a compressor, unloader and unloading valves therefor to eli'ect automatic control of the compressorl in response to receiver pressure, and means applied to at least one of said valves adapting the same to pressures below its normal range of response, saidnieans increasing the pressure area of said valvel responsive to .receiver pressure and providing a manual vcontrol device for suspending the automatic operation of said valve.

7 In combination, affluid compressor, unloader and unloading valves therefor to effeet automatic control of the compressor in response to receiver pressure, and means applied to at least one of said valves to adapt the same to pressures below its normal range of response, said means comprising a'diaphragm arranged to increase the pressure area of said valve responsive to receiver pressure.

8. In combination, a fluid compressor, unloader and unloading valves therefor to effect automaticcontrol of the compressor in response to receiver pressure, and means ap plied to at least one of said valves to adapt the same to pressures below its normal range of response, said means comprising a diaphragm interposed between the pressure area of said valve and the ressure receiver, and a ductl for conducting t e receiver pressure to said area, said 'diaphragm being arranged to increase the pressure area of said valve.

9. In combination, a fluid compressor, nnloader and unloading valves therefor to effeet automatic control of the compressor in response to receiver pressure, and means applied to at least one of said valves to adapt the saine to pressures below its normal range of response. said means comprising a casing iiiclosing a diaphragm interposed between the pressure area of said valve and receiver pressure, and a hollow member interposed between said area and said diaphragm for conducting pressure fluid to the former and for imparting the movementof the diaphragm to said area.

10. In combination, a fluid compressor, unloader and unloadingr valves therefor to ellect automatic control of the compressor in Iresponse to receiver pressure, and means applied to at least one of'said valves to adapt the same to pressures below its normal range of response, said means comprising a cas-pk ing inclosingadiapliragm interposed between the pressure area of said valve and receiver pressu're, and a tube slidably mounted in said casing and movable with said diaphragm for transmitting both pressure fluid and the movement of said dia'- phragm to'said ai'ea.

l1. In combination, a'uid coiii'pressor, unloader and unloading valves therefor to effeet automatic control of the compressor in response to receiver pressure, and means ap-` plied to at least one of said valves to adapt the same to pressures below its normal range of response, said means comprisinga casing iiiclosing a diaphragm interposed between the pressure area of said valve and receiver pressure, a hollow member interposed between said area and'said diaphragm for conducting pressure fluid to the former and for imparting the movement of the diaphragm to said area, and manual means operable through .said member for actuating said valve.

12. ln combination, a fluid compressor, unloader and unloading valves therefor to effect automatic control of' the compressor fluid and the movement of said diaphra m to said area, 'and manual means opera le' through said tube for actuating said valve,

13. In combination, a fluid compressor, valves for eflecting automatic control of the compressor in response-to receiver pressure, and means applied to at least one of said valves to adapt the lsame to pressuresl below their normal range of response, said means comprising a casing secured in the pressure fluid supply to the valve, meansl within said casing movable' in response to fluid pressure in said supply but permitting passage of pressure fluid to the valvmand means imparting the movement of lsaid first p named means to said valve.'

14. ln combination, a fluid compressor, valves `for effecting automatic controle of thecompressor4 in response to receiver pressure, and means applied to each of said valves to adapt the same to pressures below their normal range of response, said means comprising a casing secured in the pressure fluid inlet of the valve, a' fluid conducting member movably mounted in said casing and arranged to operate said valve, and means responsive to fluid pressure for niovlng said xnember whereby operation of said valve is effected both by pressure fluid admitted to said valve by said member and. by the movement of the latter.

15. Inv combination, a lluid compressor, valves for effecting automatic control of the compressor in response to receiver pressure, and means applied to at least one of said valvesrto adapt the same to pressures below` their' normal range ofk response, said means comprising a casingseeured in the pressure fluid inlet-of. the valve, a fluid conducting member movably mounted in said casing and arranged to operate said valve, and a diaphragm in said casing secured to said member for moving the latter, whereby operation of said valve is effected both by pressure fluid admitted to said valve by said member and by the movement of the latter.

16. In combination, a fluid compressor, valves for effecting automatic control of the compressor in response to receiver pressure, and means applied to each of said valves to adapt the same to pressures below their normal range'of response, said means comprisinga casing secured in the pressure fluid inlet of the valve, a tube slidably mounted in said casing, a plate fixfd upon said tube. a clamping nut upon Sill 'in said casing clamped to said plate by said 'nut to effect movement of said tube, the valve being operated by flu'id pressure ad# plunger against said nut thereby to operate said valve.

17, An adapter for the unloader vand vunloading valves of air'and gas compressors comprising a casing constructed and arranged to be secured in the pressure fluid inlet of the valve, and means therewithin cooperating with the valve for adapting thev same to pressures below the range of its normal response. Y A

18. An adapter for-the unloader and .unloading valves of air .and gascompres'sors comprising a easing' constructed and arranged to be secured in the pressure 'fluid supply to the valve, and means within said casing for increasing the effective area of the valve subjected to fluid pressure thereby to render the valve responsive to low pressures.

tube beyond said plate, `a diaphragm 19. An adapter for the unloader andunloading valves of air and gas compressors comprising a casing constructed and arranged to be secured to the valve, and means for increasing the effectivel area lof the valve subjected to fluid pressure comprising a diaphragm within said casing to be interposed between the pressure area. of the valve and the source of fluid pressure. j c

20. An adapter for the unloader and unloading valves of air and gas compressors comprising a casing constructed and arranged to be secured to the valve, a diaphragm within said casing to be interposed between the pressure area of the valve and the source of fluidpressure, and a hollow member interposed between the said area of the valve and said diaphragm .for conducting pressure fluid to the former and for transmitting the movement of said diaphragmto said area.

21. An adapter for the unloader and unloading'valves`v ofA air and gas compressors comprising a casing 'constructed and arf ranged to be secured to' the valve, 'a diaphragm within said casing to be interposed between the pressure area of the valve and the source of fluid pressure, and a tube slidably mounted in' said easing and movable with said diaphragm Afor transmitting both pressure fluid and diaphragm movement to said area. i

22. An adapter for unloader and unloading valves comprising a casing` constructed and arranged to be secured to the valve, a diaphragm Within said casing to be interposed between the pressure area of the valve and the source of fluid pressure, a hollow member interposed between the said area of the valve and said diaphragm for conducting pressure fluid to the former and for transmitting the movementV of said diaphragm to said area, and manual means operable through said member for actuating the valve. i f

23. An adapter for unloader and unloading valves comprising a casing constructed and arranged to be secured to the valve, a diaphragm within said .casing to be interposed between the pressure area of the valve and the sourcel of the fluid pressure, a-tube slidably mounted in said casing and movable with said diaphragm for transmitting both pressure fluid and diaphragm movement to n 'to be 'secured to the pressure fluid inlet of the valve, a fluid conducting member movably mounted 1n sald casing and arranged to operate the valve, and means Within said casing responsive to Huid pressure for movable in response to fluid pressure in said ing said valve While permitting the passage -supply but permitting passage of pressure 1 of pressure fluid therethrough.

25. An adapter for the automatic control valves of air and gas compressors comprising a easing constructed and arranged to he disposedlin the pressure Huid supply to the valve, means Within said casing movf fluid to the valve, and means imparting the movement of said irst named means to said valve.

Signed by me at Franklin, Pennsylvania, this 23d day of Ma' 1924.

L ON F. HFFMAN. 

